Sealed methods

Summary: This diff adds a method-level `__Sealed` attribute which controls which classes can override the method.  The core logic is implemented in `Typing_extends.bad_sealed_override_error`.

Reviewed By: enetsee

Differential Revision: D57863499

fbshipit-source-id: c1037d6c042f8f808cde1c3d0dd462346a15086b

Author: Francesco Zappa Nardelli

hphp/hack/src/decl/decl_class.ml

@@ -90,6 +90,7 @@ let element_to_class_elt
        elt_visibility = ce_visibility;
        elt_deprecated = ce_deprecated;
        elt_sort_text = ce_sort_text;
+       elt_sealed_allowlist = ce_sealed_allowlist;
        elt_overlapping_tparams = ce_overlapping_tparams;
      } :
       Decl_defs.element) : Typing_defs.class_elt =
@@ -103,6 +104,7 @@ let element_to_class_elt
     ce_deprecated;
     ce_pos;
     ce_flags;
+    ce_sealed_allowlist;
     ce_sort_text;
     ce_overlapping_tparams;
   }

hphp/hack/src/decl/decl_defs.ml

@@ -103,6 +103,7 @@ type element = {
   elt_origin: string;
   elt_visibility: ce_visibility;
   elt_deprecated: string option;
+  elt_sealed_allowlist: SSet.t option;
   elt_sort_text: string option;
   (* Derived from <<__Overlapping(_)>> attribute *)
   elt_overlapping_tparams: SSet.t option;

hphp/hack/src/decl/decl_folded_class.ml

@@ -281,8 +281,8 @@ let synthesize_typeconst_defaults
     (typeconsts, consts)
   | _ -> (typeconsts, consts)
 
-let get_sealed_whitelist (c : Shallow_decl_defs.shallow_class) : SSet.t option =
-  match Attributes.find SN.UserAttributes.uaSealed c.sc_user_attributes with
+let extract_sealed_classnames attrs : SSet.t option =
+  match attrs with
   | None -> None
   | Some { ua_params; _ } ->
     let cn_params =
@@ -294,6 +294,16 @@ let get_sealed_whitelist (c : Shallow_decl_defs.shallow_class) : SSet.t option =
     in
     Some (SSet.of_list cn_params)
 
+let get_class_sealed_allowlist (c : Shallow_decl_defs.shallow_class) :
+    SSet.t option =
+  extract_sealed_classnames
+    (Attributes.find SN.UserAttributes.uaSealed c.sc_user_attributes)
+
+let get_method_sealed_allowlist (m : Shallow_decl_defs.shallow_method) :
+    SSet.t option =
+  extract_sealed_classnames
+    (Attributes.find SN.UserAttributes.uaSealed m.sm_attributes)
+
 let get_overlapping_tparams (m : Shallow_decl_defs.shallow_method) :
     SSet.t option =
   match Attributes.find SN.UserAttributes.uaOverlapping m.sm_attributes with
@@ -387,6 +397,7 @@ let build_constructor
       elt_visibility = vis;
       elt_origin = class_name;
       elt_deprecated = method_.sm_deprecated;
+      elt_sealed_allowlist = None;
       elt_sort_text = method_.sm_sort_text;
       elt_overlapping_tparams = get_overlapping_tparams method_;
     }
@@ -521,6 +532,7 @@ let prop_decl_eager
       elt_visibility = vis;
       elt_origin;
       elt_deprecated = None;
+      elt_sealed_allowlist = None;
       elt_sort_text = None;
       elt_overlapping_tparams = None;
     }
@@ -560,6 +572,7 @@ let static_prop_decl_eager
       elt_visibility = vis;
       elt_origin = snd c.sc_name;
       elt_deprecated = None;
+      elt_sealed_allowlist = None;
       elt_sort_text = None;
       elt_overlapping_tparams = None;
     }
@@ -707,6 +720,7 @@ let method_decl_eager
     | _ -> visibility (snd c.sc_name) c.sc_module m.sm_visibility
   in
   let support_dynamic_type = sm_support_dynamic_type m in
+  let sealed_allowlist = get_method_sealed_allowlist m in
   let parent_sort_text =
     match SMap.find_opt id acc with
     | Some ({ elt_sort_text = _ as parent_text; _ }, _) -> parent_text
@@ -745,6 +759,7 @@ let method_decl_eager
       elt_visibility = vis;
       elt_origin = snd c.sc_name;
       elt_deprecated = m.sm_deprecated;
+      elt_sealed_allowlist = sealed_allowlist;
       elt_sort_text = sort_text;
       elt_overlapping_tparams = get_overlapping_tparams m;
     }
@@ -1000,7 +1015,7 @@ and class_decl
       p
       c.sc_tparams
   in
-  let sealed_whitelist = get_sealed_whitelist c in
+  let sealed_whitelist = get_class_sealed_allowlist c in
   let ua_sort_text =
     match
       Attributes.find

hphp/hack/src/decl/direct_decl_smart_constructors.rs

@@ -332,6 +332,7 @@ impl<'o, 't> DirectDeclSmartConstructors<'o, 't> {
             || name == "__NoAutoDynamic"
             || name == "__NoAutoLikes"
             || name == "__Overlapping"
+            || name == "__Sealed"
     }
 
     fn fold_string_concat(&self, expr: &nast::Expr, acc: &mut BString) -> bool {
@@ -3478,7 +3479,8 @@ impl<'o, 't> FlattenSmartConstructors for DirectDeclSmartConstructors<'o, 't> {
         }
 
         // Parse the user attributes
-        // in facts-mode all attributes are saved, otherwise only __NoAutoDynamic/__NoAutoLikes is
+        // in facts-mode all attributes are saved, otherwise only
+        // __NoAutoDynamic/__NoAutoLikes/__Overlapping and Sealed are
         let user_attributes = attributes
             .into_iter()
             .rev()

hphp/hack/src/errors/error_codes.ml

@@ -788,6 +788,7 @@ module Typing = struct
     | UnexpectedNamedArgs [@value 4500]
     | DuplicateNamedArgs [@value 4501]
     | LambdaNamedParamMismatch [@value 4502]
+    | OverrideSealed [@value 4503]
   (* Add new Typing codes here! Comment out when deprecating. *)
   [@@deriving enum, show { with_path = false }]
 

hphp/hack/src/hackrs/folded_decl_provider/fold.rs

@@ -314,6 +314,7 @@ impl<'a, R: Reason> DeclFolder<'a, R> {
             visibility: vis,
             deprecated: None,
             flags: ClassEltFlags::new(flag_args),
+            sealed_allowlist: None,
             sort_text: None,
             overlapping_tparams: None,
         };
@@ -354,6 +355,7 @@ impl<'a, R: Reason> DeclFolder<'a, R> {
             visibility: vis,
             deprecated: None,
             flags: ClassEltFlags::new(flag_args),
+            sealed_allowlist: None,
             sort_text: None,
             overlapping_tparams: None,
         };
@@ -389,6 +391,8 @@ impl<'a, R: Reason> DeclFolder<'a, R> {
             (_, v) => self.visibility(cls, self.child.module.as_ref().map(Positioned::id), v),
         };
 
+        let sealed_allowlist = self.get_method_sealed_allowlist(sm);
+
         let sort_text = match sm.sort_text.to_owned() {
             Some(text) => Some(text),
             _ => match methods.get(&meth) {
@@ -429,6 +433,7 @@ impl<'a, R: Reason> DeclFolder<'a, R> {
             visibility: vis,
             deprecated: sm.deprecated,
             flags: ClassEltFlags::new(flag_args),
+            sealed_allowlist,
             sort_text,
             overlapping_tparams: self.get_overlapping_tparams(sm),
         };
@@ -477,6 +482,7 @@ impl<'a, R: Reason> DeclFolder<'a, R> {
                 visibility: vis,
                 deprecated: sm.deprecated,
                 flags: ClassEltFlags::new(flag_args),
+                sealed_allowlist: None,
                 sort_text: sm.sort_text.to_owned(),
                 overlapping_tparams: None,
             }
@@ -823,12 +829,20 @@ impl<'a, R: Reason> DeclFolder<'a, R> {
         }
     }
 
-    fn get_sealed_whitelist(&self) -> Option<IndexSet<TypeName>> {
+    fn get_class_sealed_whitelist(&self) -> Option<IndexSet<TypeName>> {
         (self.child.user_attributes.iter())
             .find(|ua| ua.name.id() == *sn::user_attributes::uaSealed)
             .map(|ua| ua.classname_params().iter().copied().collect())
     }
 
+    fn get_method_sealed_allowlist(&self, method: &ShallowMethod<R>) -> Option<IndexSet<TypeName>> {
+        method
+            .attributes
+            .iter()
+            .find(|ua| ua.name.id() == *sn::user_attributes::uaSealed)
+            .map(|ua| ua.classname_params().iter().copied().collect())
+    }
+
     fn get_overlapping_tparams(&self, method: &ShallowMethod<R>) -> Option<IndexSet<Symbol>> {
         method
             .attributes
@@ -974,7 +988,7 @@ impl<'a, R: Reason> DeclFolder<'a, R> {
             });
         self.rewrite_class_consts_for_enum(enum_inner_ty, &ancestors, &mut consts);
 
-        let sealed_whitelist = self.get_sealed_whitelist();
+        let sealed_whitelist = self.get_class_sealed_whitelist();
 
         let deferred_init_members = self.get_deferred_init_members(&constructor.elt);
 

hphp/hack/src/hackrs/ty/decl/folded.rs

@@ -52,6 +52,7 @@ pub struct FoldedElement {
 
     /// If the element is deprecated, this holds the deprecation message.
     pub deprecated: Option<Bytes>,
+    pub sealed_allowlist: Option<IndexSet<TypeName>>,
     pub sort_text: Option<String>,
     pub overlapping_tparams: Option<IndexSet<Symbol>>,
 }

hphp/hack/src/hackrs/ty/decl/from_oxidized.rs

@@ -608,6 +608,7 @@ impl From<o::decl_defs::Element> for folded::FoldedElement {
             origin: x.origin.into(),
             visibility: x.visibility.into(),
             deprecated: x.deprecated.map(Into::into),
+            sealed_allowlist: x.sealed_allowlist.map(map_k),
             sort_text: x.sort_text,
             overlapping_tparams: x.overlapping_tparams.map(map_k),
         }

hphp/hack/src/hackrs/ty/decl/to_oxidized.rs

@@ -558,6 +558,7 @@ impl ToOxidized for folded::FoldedElement {
                 .deprecated
                 .map(|x| String::from_utf8_lossy(x.as_bytes()).to_string()),
             flags: self.flags,
+            sealed_allowlist: self.sealed_allowlist.to_oxidized(),
             sort_text: self.sort_text,
             overlapping_tparams: self.overlapping_tparams.to_oxidized(),
         }

hphp/hack/src/oxidized/gen/decl_defs.rs

@@ -3,7 +3,7 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the "hack" directory of this source tree.
 //
-// @generated SignedSource<<b6ee7f07f15dfff40b614f3a29222450>>
+// @generated SignedSource<<36880d974d036f18d61136467e3900e6>>
 //
 // To regenerate this file, run:
 //   buck run @fbcode//mode/dev-nosan-lg fbcode//hphp/hack/src:oxidized_regen
@@ -169,6 +169,7 @@ pub struct Element {
     pub origin: String,
     pub visibility: CeVisibility,
     pub deprecated: Option<String>,
+    pub sealed_allowlist: Option<s_set::SSet>,
     pub sort_text: Option<String>,
     pub overlapping_tparams: Option<s_set::SSet>,
 }